Atrial fibrillation (AF) remains the most prevalent cardiac rhythm disturbance and it is becoming more common in an ageing population. As well as causing distressing symptoms, it is a leading cause of stroke. Thankfully, catheter ablation techniques are evolving to provide increasingly safe and effective solutions.
When medicines fail to control the symptoms of AF, or their side effects are not tolerated, then catheter ablation - performed with transcatheter access via the leg veins - can provide an effective long term solution to restore a normal heart rhythm and allow medicines to be discontinued.
A recent evolution in catheter technology has revolutionised the field with the ability to make the procedure safer, reduce radiation exposure, and improve success rates. The SmartTouch catheter measures micro-deformations of a precision spring connecting the catheter shaft and tip. This allows the operator, for the first time, to know exactly how much pressure the catheter is exerting on the wall of the heart.
Only released in the USA in February 2014, Royal Brompton Hospital have been pioneering the use of this technology since 2011 and now is one of the world's most experienced hospitals using it.
Having already shown that the technology improves the immediate procedural success rate in a previous study (with 100 per cent of pulmonary veins successfully isolated), in a multicentre study of 600 patients we have now found that the use of SmartTouch technology also significantly improves long term outcomes as well as reducing radiation exposure.
Dr Julian Jarman’s experience:
The critical thing is that the procedure is performed safely. Using SmartTouch technology in every case certainly helps this. But other factors are equally important. All patients at Royal Brompton Hospital have general anaesthesia, allowing the consultant to perform detailed echocardiographic imaging throughout the procedure, which excludes blood clots before starting, and also helps guide the procedure.
Meticulous attention to sheath irrigation has also been crucial to prevent strokes. During the last three years (up until 2014) the rate of stroke at Royal Brompton Hospital has been 0 per cent amongst 821 left atrial ablation procedures, and this reflects careful application of the latest techniques.
Most patients with AF have a yearly risk of stroke running between two and seven per cent. Although the results of randomised trials are awaited, emerging data are suggesting that the risk of stroke is reduced when a normal heart rhythm is restored by this procedure.
Tailoring the procedure to the patient
While the great majority of patients with paroxysmal (intermittent) AF can achieve excellent long term outcomes, those with persistent (continuous) AF, while still usually having good outcomes, can sometimes be more challenging to treat.
In an international collaboration with an experienced Californian centre, Silicon Valley Cardiology, we have been defining the factors which predict the best outcomes from persistent AF ablation, even identifying groups of patients with long term outcomes superior to those with paroxysmal AF.
The FLAME Score is a novel scoring system we have developed to allow us to better advise our AF patients and tailor their procedures individually. A lower score predicts a better outcome.
Two of the most important factors in predicting procedural outcome are the duration of AF and the left atrial size, which tends to increase over time. The best outcomes are achieved when the procedure is performed earlier in the natural history of the disease.
Challenging case mix
The collaboration with Silicon Valley Cardiology also demonstrated the complexity of the case mix treated at Royal Brompton Hospital as a specialist national referral centre.
The average FLAME Score of our patients was significantly higher than in the US hospital, while the proportion of patients with the most challenging ‘extreme comorbidities’, such as structural congenital heart disease, was almost three times as high (11 per cent compared to 4 per cent).
In conclusion, catheter ablation can transform the outlook for patients with AF. However, applying the latest techniques and technologies is essential to ensure a safe and effective procedure.
Consultant cardiologist and electrophysiologist